1. Field of the Invention
The present invention relates to a connection tube for a fuel tank and particularly to a fuel tank mounted on a vehicle for filling fuel.
2. Description of the Related Art
Recently, fuel tanks which are made of plastic by blow molding become a trend as fuel tanks mounted on vehicles from a viewpoint of rust prevention and a lightweight requirement. Generally, to the fuel tank are attached various structural parts such as a vent valve for maintaining an internal pressure of the fuel tank by introducing a fuel vapor gas at a space above a liquid level to the outside of the fuel tank and a fuel service valve (backflow valve) connected to a filler tube. In a case of the plastic fuel tank, these structural parts are generally attached to the fuel tank by a heat welding method from a viewpoint of simplifying a production process.
U.S. Pat. No. 6,808,209 discloses a connection tube for a plastic fuel tank as an attachment. The connection tube has an outer tube connectable to a filler tube and an inner tube, formed of an HC (hydrocarbon) barrier material which is different from a material of the outer tube, for receiving and feeding fuel to the fuel tank.